Prosecutors Step Up Armstrong Probe

Investigators Subpoena Documents and a Witness in Bid to Prove the Tour de France Champion Used Banned Substances

By

Reed Albergotti And

Vanessa O'Connell

Updated July 27, 2010 12:01 a.m. ET

Federal prosecutors handling an investigation into cheating in professional cycling have subpoenaed documents from an arbitration case that sought to prove that Lance Armstrong used performance-enhancing drugs.

The documents contain depositions from former teammates and associates of the seven-time Tour de France champion during a period when a promotions company was trying to prove that Mr. Armstrong employed banned drugs and...